Relay



July 6, 1943. D. A. MILLER RELAY Filed Nov. 1o, 1941 Insulah'm.

gums/wm Insulaon Patented July 6, 1943 RELAY Donald A. Miller, nnuucum Heights, Md., munor, by direct and inecne assignments, to National Electric Control Company, a corporation of Maryland Application November 10, 1941, Serial No. 418,578

(Cl. 20o-110) Claims.

This application is a continuation in part of my copending application Ser. No. 288,234, led

August 3, 1939, Relay.

The principal object of my invention, generally considered, is to provide a relay of rugged construction but of such sensitivity as to respond to extremely low operating current.

Another object ofl the invention is to provide a relay in which a movable coil is held in .aA predetermined position by spring means, the operating connector or switch member being controlled by movementof the coil and insulated therefrom.

Still another object of the invention is to provide an extremely sensitive relay having an operating differential as low as one-quarter microampere.

Still another objectof the invention is to provide a relay in which the operating diilerential may be adjusted from a minimum of one-quarter microampere to a maximum of eighteen mi- V croamperes.

Still another object of the invention is to provide a sensitive relay adapted to operate on current as low as ve microamperes but of such rugged construction as to be unaffected by vibrations or jars and capable of continued operation irrespective of the position in which the relay is placed.

A still further object of the invention is to provide a relay with mercury contact cups, such cups being of such metal as to retain the mercury therein by cohesive action to thus cause the mercury 'to form a film over the surface of the cup of substantially uniform depth rather than forming a globule in the cup recess.

Other objects of my invention will be pointed out in connection with'the more detailed description vof the single embodiment thereof illustrated in the accompanying drawing, in

which:

Figure 1 is a front elevational view of a relay constructed in accordance with my invention..

Figure 2 is a rear elevational view.

Figure 3 is a side elevational view.

Figure 4 is a view partially in horizontal cross section showing the relay and its accompanying housing greatly lenlarged in order to illustrate certain details of construction.

Figure 5 is a fragmentary detail view, partially in elevation and partially in section showing the contact members and the limiting means for maintaining the movement of the contact members within specified limits.

Figure 6 is a fragmentary cross sectional view showing one method of insulating the armature operating contact member.

Figure 7 is a view similar to Figure 5 showing a modification thereof.

Throughout the several views like reference characters indicate corresponding parts.

The numeral 1- designates generally a housing in which the relay is adapted to be secured. This housing preferably comprises a base plate 2, a cylindrical portion 3 and a cover plate 4. The base plate and cover plate are each preferably secured to the cylindrical member 3 by screws 4*I and 4h prior to which a sealing compound is preferably applied to the marginal edges of the member 3 so that when the parts are assembled the housing or casing I is hermetically sealed to prevent the entrance of dirt, moisture or other foreign matter.

It will be obvious from the drawing that the relay generally designated by the reference numeral 5 is 'secured to the plate 4 by means of screws 6, the latter being threadably receivedwithin posts 1, each of Awhich is secured to one of the pole pieces 8 vof 'the relay.

v The permanent magnet members 9 are adapted to engage and be secured to the pole pieces 8, preferably by screws or bolts 9a and form with the pole pieces B a housing for the movable or rotatable coil III. Each pole piece 8 is provided with an inward extension II.ha''ing a concaved face I2 corresponding in curvature to the radius of the rotatable coil.

In the preferred embodiment of the invention of the pivots for the movable or rotatablev coilv l0, the opposite bearing of the coil being formed in the bridge member I3.

l Secured in spaced relation to the bridge mem, ber I3, preferably by means of bolts I1, is am other insulated plate Il to which are secured' cups I9 as well as the limiting stop members 20 and 2l. Connected respectively to each of the cups `|9-are leads 22 by means of which the relay is connected to the device to. be operated.

'I'hese leads extend through the plate 4, preferably in the form of binding posts 24. The leads for the coil operating current extend from the binding posts also on the plate 4 to the coil and to the magnetic circuit as is usual and customary.

Extending upwardly from the shaft 26 of the rotatable coil adjacent the bridge piece I3 is a goose neck member 21 and interposed in the neck of said member 21 is an insulating piece 2B, best shown in Figure 6, by means of which the coil is insulated from the circuit formed by the contact points 29 and 30 carried by the member 21.

It will be seen from Figure 5 that I have provided, by means of the depending portion of the member 29 and the immediately adjacent cup Il, a two-part connector and by positioning the center of the concavity on the said cup I8 adjacent the center on which the coil ID moves or rotates, the part 2S of the connector merely rocks about its bearing and has practically no relative movement with respect thereto other than such rocking movement. The extension or arm of the member 28 and the other cup I9 serve as a, switch to make or break the relay controlled circuit. Since by the construction illustrated the end of the member 30 moves in the arc of a circle, the center of which is the opposite cup, the degree of penetration of the end of the member 3|) into the mercury film can be readily controlled, as hereinafter pointed out.

The limit stops 20 and 2| are adapted to limit the rotation of the coil l0 by engaging respectively the opposite sides of the goose neck member 21, the stop 20 being so positioned as tomaintain the goose neck in substantially vertical position and the stop 2| being positioned to be engaged by the opposite surface of thegoose neck to limit the extent of immersion in the mercury of the switch point of the arm 30. By adjusting the position of the stops and/or by regulating the tension of the springs 3l, the operating differential of the relay may be adjusted, as set forth in the objects of the invention, between one-quarter of a microampere and approximately eighteen microamperes.

The cups I9 are formed of metal having an amnity for mercury and I have found that by causing the mercury to be deposited within each cup and then subjecting the c up to a rapid rotation about its vertical axis a mercury lm of substantially uniform depth will be applied to r the entire surface of the cup and globules of mercury, such as are usually found in connection with relays of this character, are entirely avoided. I have ,also found that the mercury will cohere to the surface of the cups and that the force of such coherence is much greater than the force of gravity which may be caused to act upon the mercury lm so that the form of the mercury contact film is not altered irrespective of the position in which the cup may be placed upon the positioning of the relay. The force of coherence is also of sufficient vintensity to prevent the dislodgement of the mercury irrespective of the jars and shocks to which the relay may be subjected so that in service jars that would loosen or displace the globules of mercury and hence prevent the operation of a relay have no effect upon my mechanism.

By securing the relay and its contacts to the plate 4 it is a simple matter to assemble and disassemble the relay in order to make any adjustment necessary and at the same time to protect the relay, which is hermetically sealed, against dirt. dust or moisture.

In Figure 7 I have illustrated a slight modification of the manner of mounting the twopart connector. The point of the connector part 29 is bent so as to engage the cup I9, the latter extending in a horizontal direction instead of vertically. Since the center of the cup is positioned in alinement with the axis of rotation of the coil it will be apparent that in the modified form the point will rotate about the same center as the coil.

From the foregoing description it will be apparent that I have designed a relay of such sensitivity as to respond to current generated by either photo-electric or selenium cells and at the same time the relay and switch are of such construction as to withstand jolts and jars without detriment to the sensitivity of the apparatus. The relay, therefore, may be located on machines and will operate Without regard to the vibrations produced by such mounting. By adjusting the relay so as to provide the proper amount of operating differential and then proceeding to seal the same withinthe casing or housing, lchanges in temperature or the presence of dust in the atmosphere will have no effect upon the operation of the relay and once adjusted it will continue to operate on the desired and prede termined current.

The switch mechanism is of sufficiently rugged construction to permit, Without detriment to the switch or other members of the relay, of an operating current as great as two hundred microamperes.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent, is:

1. In a relay, the combination with a rotatable coil, of a switch member comprising a two-part connector, one of said parts being movable with and insulated from the said coil, and a pair oi spaced cupshaped members one of which forms a fixed part of said connector, the other of said members cooperating with an arm carried by the movable connector member, cavities within said cup members having the interior surfaces thereof coated with a conducting film of substantially uniform depth, said film being cohesively secured to the adjacent surface of each cup.

2. In a relay, the combination with a rotatable coil, of spring means for maintaining said coil in a predetermined position, means for rotating said coil against the tension of said spring, and a switch operable by a movement of said coil, said switch involving a multi-part device having fixed and movable members, said movable member being movable with said coil and insulated therefrom, said last named part being rockable about a point substantially coincident with the center of movement of said coil.

3. In a relay, the combination with a rotatable coil, of a switch member including a movable arm and a mercury cup cooperating therewith, insulating means for connecting said arm to said coil, an extension of said arm engaging a 'second mercury cup, said last mentioned cup being in substantial alinement with the pivotal axis of said coil, said extension having a rocking engagement with said last named cup on being moved in response to the movement of the coil, and means for limiting the movement of said coil to a predetermined amount.

4. In a relay, the combination with a rotatable coil. a switch: member operatively connected of said coil, a contact arm connected to the movable part of said connector, and a cupshaped member cooperating with said arm, said cup-shaped member having the cavity therein coated with a conducting lm of mercury cohesively secured thereto. f

5. In a relay, the combination with a rotatable coil, of means for actuating said coil, means for returning said co'i1 to a predetermined position, insulating means for connecting to said coil the movable part of a two-part connector, the other part of said connector comprising a cup, means for electrically connecting the parts of said connector, and a switch arm' rigidly connected to the movable part of said connector and movable therewith, the movable part of said connector rotating substantially about the cen- 10 ter of rotation of said coil.

DONALD A. Mum. f 

